In this Vox Talk from 2008, Alvin Roth talks to Romesh Vaitilingam about some of the research for which he was recently awarded the Nobel Memorial Prize in Economic Sciences (with Lloyd Shapley). They discuss his work designing markets for kidney exchange, mechanisms for school choice in New York and Boston, and efficient systems for getting doctors and economists into their first jobs. Roth also explains the significance of repugnance as a constraint on markets.